Shearing sequence for a blowout preventer

ABSTRACT

The present disclosure relates to a system that includes a body surrounding a bore, a first ram disposed adjacent a first end of the body and coupled to a first actuator, a second ram disposed adjacent to a second end opposite the first end of the body and coupled to a second actuator, and a controller communicatively coupled to the first and second actuators. The controller is configured to actuate the first actuator to direct the first ram toward a tubular string disposed in the bore, such that the first ram aligns the tubular string with a first shearing portion of the second ram when the first ram is in an actuated position, and to actuate the second actuator, after actuating the first actuator, to direct the second ram toward the tubular string such that the first and second rams completely cut the tubular string.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of European Patent Application No.15307172.5, entitled “Shearing Sequence for a Blowout Preventer”, filedDec. 30, 2015, which is herein incorporated by reference in itsentirety.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

A blowout preventer (BOP) stack may be installed on a wellhead to sealand control an oil and gas well during drilling operations. A tubularstring may be suspended inside a drilling riser and extend through theBOP stack into the wellhead. During drilling operations, a drillingfluid may be delivered through the tubular string and returned through abore between the tubular string and a casing of the drilling riser. Inthe event of a rapid invasion of formation fluid in the bore, commonlyknown as a “kick,” the BOP stack may be actuated to seal the drillingriser from the wellhead and to control a fluid pressure in the bore,thereby protecting well equipment disposed above the BOP stack.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features, aspects, and advantages of the present disclosure willbecome better understood when the following detailed description is readwith reference to the accompanying figures in which like charactersrepresent like parts throughout the figures, wherein:

FIG. 1 is a schematic diagram of a mineral extraction system, inaccordance with an embodiment of the present disclosure;

FIG. 2 is a perspective view of an embodiment of a BOP stack assemblythat may be used in the mineral extraction system of FIG. 1, inaccordance with an embodiment of the present disclosure;

FIG. 3 is a cross-sectional top view of a portion of a BOP of the BOPstack assembly of FIG. 2, illustrating first and second rams in an openposition, in accordance with an embodiment of the present disclosure;

FIG. 4 is a cross-sectional top view of the portion of the BOP of theBOP stack assembly of FIG. 3, illustrating the first ram in a secondposition and the second ram in the open position, in accordance with anembodiment of the present disclosure;

FIG. 5 is a schematic of a portion of the BOP of FIG. 4, illustrating ahydraulic circuit that may be utilized to direct the first ram into thesecond position, in accordance with an embodiment of the presentdisclosure;

FIG. 6 is a cross-sectional top view of the portion of the BOP of FIGS.3-5, illustrating both first and second rams in a second position, inaccordance with an embodiment of the present disclosure;

FIG. 7 is a schematic of the portion of the BOP of FIG. 5, illustratingthe hydraulic circuit of FIG. 5 that may be utilized to direct thesecond ram into the second position, in accordance with an embodiment ofthe present disclosure;

FIG. 8 is a schematic of the portion of the BOP of FIGS. 5 and 7,illustrating the hydraulic circuit of FIGS. 5 and 7 that may be utilizedto direct the first and second rams back into the open position, inaccordance with an embodiment of the present disclosure; and

FIG. 9 is a block diagram of a process that for the BOP of FIGS. 1-8that may be utilized to carry out an enhanced shearing sequence, inaccordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present disclosure will bedescribed below. These described embodiments are only exemplary of thepresent disclosure. Additionally, in an effort to provide a concisedescription of these exemplary embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

Embodiments of the present disclosure relate to a blowout preventer(“BOP”) system that may completely shear (e.g., cut) a tubular string toenhance a seal of a wellbore when blowout conditions are detected. A BOPmay be included at a wellhead to block a fluid from inadvertentlyflowing from the wellhead to a drilling platform (e.g., through adrilling riser). For example, pressures may fluctuate within a naturalreservoir, which may lead to a surge in fluid flow from the wellheadtoward the drilling platform when the pressure reaches a thresholdvalue. To block fluid from flowing toward the drilling platform duringblowout conditions, the BOP may be actuated to cut the tubular stringand seal the drilling riser from the wellhead (e.g., by covering a borein the BOP coupling the wellhead to the drilling riser). In accordancewith embodiments of the present disclosure, at least one BOP of a BOPstack may include shearing rams that may be configured to cut thetubular string and enhance a seal of the bore extending through the BOP.

In accordance with present embodiments, a BOP system may be operatedutilizing an enhanced shearing sequence to enhance a seal between thewellhead and the drilling riser during blowout. For example, the BOPsystem may be configured to actuate a first ram of the BOP from an openposition toward the tubular string and into the bore of the BOP. Thefirst ram may contact the tubular string and align the tubular stringwith a shearing portion of a second ram of the BOP before the second ramis actuated. The second ram may then be actuated such that shearingportions of both the first and second rams fully contact the tubularstring and perform a cut (e.g., a complete cut) of the tubular string.Completely cutting or shearing the tubular string may enable the firstand second rams to completely cover the bore of the BOP, and thus, forman enhanced seal between the wellhead and the drilling riser.

With the foregoing in mind, FIG. 1 is a schematic of an embodiment of amineral extraction system 10. The mineral extraction system 10 includesa vessel or platform 12 at a surface 14. A BOP stack assembly 16 ismounted to a wellhead 18 at a floor 20 (e.g., a sea floor for offshoreoperations). A tubular drilling riser 22 extends from the platform 12 tothe BOP stack assembly 16. The riser 22 may return drilling fluid or mudto the platform 12 during drilling operations. Downhole operations arecarried out by a tubular string 24 (e.g., drill string, productiontubing string, or the like) that extends from the platform 12, throughthe riser 22, through a bore 25 of the BOP stack assembly 16, and into awellbore 26.

To facilitate discussion, the BOP stack assembly 16 and its componentsmay be described with reference to an axial axis or direction 30, alongitudinal axis or direction 32, and a lateral axis or direction 34.As shown, the BOP stack assembly 16 includes a BOP stack 38 havingmultiple BOPs 40 (e.g., ram BOPs) axially stacked (e.g., along the axialaxis 30) relative to one another. As discussed in more detail below,each BOP 40 includes a pair of longitudinally opposed rams andcorresponding actuators 42 that actuate and drive the rams toward andaway from one another along the longitudinal axis 32. Although four BOPs40 are shown, the BOP stack 38 may include any suitable number of BOPs(e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more). Additionally, the BOPstack 38 may include any of a variety of different types of rams. Forexample, in certain embodiments, the BOP stack 38 may include one ormore BOPs 40 having opposed shear rams or blades configured to sever thetubular string 24 and seal off the wellbore 26 from the riser 22 and/orone or more BOPs 40 having opposed pipe rams configured to engage thetubular string 24 and to seal the bore 25 (e.g., an annulus around thetubular string 24).

FIG. 2 is a perspective view of an embodiment of the BOP stack assembly16. As discussed above, the BOP stack 38 includes multiple BOPs 40axially stacked (e.g., along the axial axis 30) relative to one another.As shown, the BOP stack 38 also includes one or more hydraulicaccumulators 45. The hydraulic accumulators 45 may store and/or supply(e.g., via one or more pumps) hydraulic pressure to the actuators 42that are configured to drive the rams of the BOPs 40. In certainembodiments, the hydraulic accumulators 45 and/or the actuators 42 maybe communicatively coupled to a controller 46. The controller 46 may beconfigured to send signals to the hydraulic accumulators 45, theactuators 42, and/or one or more pumps to drive the rams of the BOPs 40when blowout conditions exist. For example, the controller 46 mayreceive feedback from one or more sensors 47 (e.g., pressure sensorsand/or flow sensors) that may monitor conditions of the wellbore 26(e.g., a pressure of the fluid in the wellbore 26). The controller 46may include memory 48 that stores threshold values indicative of blowoutconditions. Accordingly, a processor 49 of the controller 46 may send asignal instructing the hydraulic accumulators 45, the actuators 42,and/or the one or more pumps to drive and/or actuate the rams whenmeasured feedback received from the controller 46 meets or exceeds suchthreshold values.

FIG. 3 is a cross-sectional top view of a portion of one BOP 40 with afirst ram 50 and a second ram 52 in an open position 54. In the openposition 54, the first ram 50 and the second ram 52 are withdrawn orretracted from the bore 25, do not contact the tubular string 24, and/ordo not contact the corresponding opposing ram 50, 52. As shown, the BOP40 includes a body 56 (e.g., housing) surrounding the bore 25. The body56 is generally rectangular in the illustrated embodiment, although thebody 56 may have any cross-sectional shape, including any polygonalshape or an annular shape. A bonnet assembly 60 is mounted to the body56 (e.g., via threaded fasteners). The bonnet assembly 60 may supportthe actuators 42, which each include a piston 62 and a connecting rod63. As shown in the illustrated embodiment, when in the open position54, the first ram 50 is generally adjacent to a first end 64 of the body56 and the second ram 52 is generally adjacent to a second end 65opposite the first end 64 of the body 56. The actuators 42 may drive thefirst and second rams 50, 52 toward and away from one another along thelongitudinal axis 32 and through the bore 25 to shear the tubular string24 and/or to seal the bore 25 (e.g., the annulus about the tubularstring 24).

The first ram 50 may include a first shearing portion 66, and the secondram 52 may include a second shearing portion 68. The first shearingportion 66 may include a first width 70 that is greater than a diameter72 of the tubular string 24, such that the first shearing portion 66 maycut through the entire tubular string 24. Similarly, the second shearingportion 68 may include a second width 74 that is greater than thediameter 72 of the tubular string 24. Accordingly, when the first andsecond shearing portions 66, 68 are aligned with the tubular string 24and are directed toward one another, the tubular string 24 may becompletely cut to seal the bore 25. However, in certain embodiments, thefirst and second shearing portions 66, 68 may not extend across anentire diameter 76 of the bore 25. For example, the bore 25 may includean annular opening 78 that surrounds the tubular string 24. Although thefirst and second shearing portions 66, 68 may not extend across theentire diameter 76 of the bore 25, the first and second rams 50, 52 mayinclude non-shearing portions 80, 82, respectively, that are configuredto cover portions of the bore 25 that may be left uncovered by theshearing portions 66, 68. Accordingly, during blowout conditions, thefirst and second rams 50, 52 may be moved along the longitudinal axis 32toward one another to seal the bore 25. To completely seal the bore 25,the first and second rams 50, 52 may cut through the tubular string 24.

In some embodiments, the shearing portions 66, 68 may include differentgeometries. For example, as shown in the illustrated embodiment of FIG.3, the first shearing portion 66 may include a substantially linear(e.g., a generally straight line) geometry. The second shearing portion68 may include an indented (e.g., two lines forming an obtuse angle withrespect to a joint 83) geometry. It should be noted that in otherembodiments, the first and second shearing portions 66, 68 may includeany suitable geometry for cutting the tubular string 24 and sealing thebore 25. In some embodiments, the first shearing portion 66 and thesecond shearing portion 68 may be offset with respect to the axial axis30 (see FIG. 5). For example, the first shearing portion 66 may be at afirst position along the axial axis 30 such that the second shearingportion 68 may be configured to be positioned above or below (e.g., withrespect to the axial axis 30) the first shearing portion 66 (e.g., thefirst and second shearing portions 66, 68 may not directly contact oneanother) when both the first and second shearing portions 66, 68 are ina second position (see FIG. 6). Such a configuration may enable both thefirst and second shearing portions 66, 68 to completely pass through thetubular string 24 when blowout conditions exist.

As shown in the illustrated embodiment of FIG. 3, the tubular string 24may not be positioned in a center of the bore 25 with respect to therams 50, 52. In other words, the tubular string 24 may not be alignedwith the first shearing portion 66 of the first ram 50 and/or the secondshearing portion 68 of the second ram 52. Accordingly, driving the firstand second rams 50, 52 toward one another along the longitudinal axis 32simultaneously may not enable both the first shearing portion 66 and thesecond shearing portion 68 to contact a complete circumference 84 (e.g.,outer surface) of the tubular string 24. As the first and second rams50, 52 are driven toward the tubular string 24, the first ram 50 mayapply a first force to the tubular string 24 in a first direction 86,and the second ram 52 may apply a second force to the tubular string 24in a second direction 88 opposite the first direction 86. In someembodiments, the first force and the second force applied in opposingdirections 86, 88 may be substantially equal, such that the tubularstring 24 may remain substantially stationary when the first and secondrams 50, 52 are simultaneously driven toward the tubular string 24 andcontact the tubular string 24 at approximately the same time.

The tubular string 24 may be cut as the first and second shearingportions 66, 68 contact the circumference 84 of the tubular string 24.However, because the first shearing portion 66 and/or the secondshearing portion 68 may not be aligned with the entire circumference 84of the tubular string 24, a portion 90 of the tubular string 24 may notbe cut by the rams 50, 52. The portion 90 of the tubular string 24 leftuncut may block the rams 50, 52 (e.g., the non-shearing portions 80, 82)from completely contacting one another, such that the bore 25 includes agap or opening that may enable fluid to flow from the wellbore 26 (e.g.,wellhead) and into the drilling riser 22 when blowout conditions occur.Accordingly, the bore 25 may not be completely sealed by the BOP 40 as aresult of the uncut portion 90 of the tubular string 24. Therefore, itis now recognized that an enhanced sequence of actuating the rams 50, 52is desired to enhance the seal of the bore 25.

For example, FIG. 4 is a cross-sectional top view of a portion of theBOP 40 of the BOP stack 38, illustrating the first ram 50 in a secondposition 100 and the second ram 52 in the open position 54. Accordingly,FIG. 4 illustrates the BOP 40 operating with an enhanced sequence thatincludes driving the first ram 50 into the second position 100 beforedriving the second ram 52 toward the tubular string 24 (and the firstram 50). It should be noted that in other embodiments, the second ram 52may be actuated before the first ram 50 to align the tubular string 24,and then the first ram 50 may be actuated to cut the tubular string 24.

As shown in the illustrated embodiment of FIG. 4, as the first ram 50 isdriven into the second position 100, the first ram 50 aligns the tubularstring 24, the first shearing portion 66, and the second shearingportion 68 of the second ram 52 along an axis 101. In some embodiments,the first ram 50 may align the tubular string 24 by contacting thetubular string 24 and directing the tubular string 24 in the firstdirection 86. As the tubular string 24 moves in the direction 86, it maybe guided along an inner diameter 102 of the bore 25 (e.g., in adirection 104 about the axial axis 30). Accordingly, when the first ram50 is in the second position 100, the tubular string 24 may contact aportion 106 of the inner diameter 102 closest to the second shearingportion 68 of the second ram 52, and thus be substantially aligned withthe second shearing portion 68 along the axis 101.

Therefore, the position of the tubular string 24 within the bore 25 maybe adjusted by the first ram 50 and/or the second ram 52 (e.g., thetubular string 24 is not substantially fixed with respect to the bore25). Therefore, actuating the first ram 50 before the second ram 52 (orvice versa) enables the tubular string 24 to be guided along the innerdiameter 102 of the bore 25 to a position that substantially aligns theentire diameter 72 of the tubular string 24 with the first shearingportion 66 and the second shearing portion 68 along the axis 101.

In some embodiments, to actuate the first ram 50 without actuating thesecond ram 52, a sequencing valve 120 may be utilized. For example, FIG.5 is a schematic of the of a portion of the BOP 40, illustrating thefirst ram 50 in the second position 100 and the second ram 52 in theopen position 54. The illustrated embodiment of FIG. 5 shows a hydrauliccircuit 122 that may direct hydraulic fluid 124 from one or more of thehydraulic accumulators 45 to the actuators 42 via a first pump 125. Itshould be noted that in other embodiments, the actuators 42 may bepneumatic such that the BOP 40 includes a pneumatic circuit (e.g., thatincludes a compressor) instead of the hydraulic circuit 122. In someembodiments, the hydraulic circuit 122 may include the sequencing valve120 to perform the enhanced shearing sequence. For example, thesequencing valve 120 may be configured to direct the hydraulic fluid 124toward a first hydraulic chamber 126 of a first actuator 127 that drivesthe first ram 50 along the longitudinal axis 32 (e.g., the hydraulicfluid 124 directs the first actuator 127 along the longitudinal axis 32by increasing the pressure in the first hydraulic chamber 126 to drivethe first actuator in the direction 86). Additionally, the sequencingvalve 120 may be configured to block the hydraulic fluid 124 fromflowing toward a first hydraulic chamber 128 of a second actuator 129configured to drive the second ram 52 along the longitudinal axis 32.Therefore, the sequencing valve 120 enables the first ram 50 to beactuated along the longitudinal axis 32, while generally maintaining thesecond ram 52 in the open position 54.

As the hydraulic fluid 124 enters the first hydraulic chamber 126 anddirects the first actuator 127 in the direction 86, a second hydraulicfluid 130 may flow from a second hydraulic chamber 131 of the firstactuator 127 toward one or more of the hydraulic accumulators 45. Insome embodiments, pressure may increase in the second hydraulic chamber131 as the first actuator 127 moves in the direction 86 (e.g., as aresult of a reduction of a volume of the second hydraulic chamber 131caused by the piston 62). Accordingly, the pressure within the secondhydraulic chamber 131 may urge the second hydraulic fluid 130 through anoutlet 132 of the second hydraulic chamber 131 and toward one or more ofthe hydraulic accumulators 45.

In some embodiments, the sequencing valve 120 may include a mechanism(e.g., a spring or other biasing member) that blocks an outlet 134 ofthe sequencing valve 120 coupled to the second actuator 129 until athreshold pressure of the hydraulic fluid 124 is reached. Accordingly,the sequencing valve 120 may direct hydraulic fluid 124 toward the firstactuator 127 and block the hydraulic fluid 124 from flowing toward thesecond actuator 129 until the first ram 50 is in the second position100. The threshold pressure of the sequencing valve 120 may be set(e.g., manually or electronically via the controller 46) at a pressurecorresponding to the hydraulic fluid 124 when the first ram 50 is insecond position 100. When the threshold pressure is met and/or exceeded,the outlet 134 of the sequencing valve 120 may be configured to opensuch that the hydraulic fluid 124 is directed toward the second actuator129.

When the sequencing valve 120 is triggered (e.g., the threshold pressureis met and/or exceeded to open the outlet 134), the second ram 52 may bedirected toward the first ram 50 (and the tubular string 24) by thesecond actuator 129. For example, FIG. 6 is a cross-sectional top viewof the BOP 40, illustrating the first ram 50 in the second position 100and the second ram 52 in a second position 140. As shown in theillustrated embodiments, the second ram 52 contacts the tubular string24 as it moves toward the second position 140 and applies a force in thedirection 88 such that the tubular string 24 is cut. The first ram 50remains substantially stationary in the second position 100 and mayapply an opposing force (e.g., reactive force) to the tubular string 24in the direction 86 to keep the tubular string 24 substantiallystationary with respect to the bore 25 as the second ram 52 moves towardthe second position 140. Accordingly, as the second ram 52 moves towardthe second position 140, the second shearing portion 68 and/or the firstshearing portion 66 of the first ram 50 may cut through the tubularstring 24, thereby sealing the bore 25.

To actuate the second ram 52, the outlet 134 of the sequencing valve 120coupled to the second actuator 129 may be opened. For example, FIG. 7 isa schematic of the portion of the BOP 40, illustrating the first ram 50in the second position 100 and the second ram 52 in the second position140. As shown in the illustrated embodiment of FIG. 7, the hydraulicfluid 124 flows toward the second actuator 129, thereby driving thesecond ram 52 in the second direction 88 toward the tubular string 24and the first ram 50.

When the second ram 52 moves in the direction 88, the second shearingportion 68 may contact the tubular string 24 and cut the tubular string24, thereby sealing the bore 25. As discussed above, the first shearingportion 66 and the second shearing portion 68 may be offset from oneanother with respect to the axial axis 30. For example, the firstshearing portion 66 may form a ledge 160 at a first distance 162 from abottom surface 164 of the BOP 40. Additionally, the second shearingportion 68 may include a surface 166 that is a second distance 168 fromthe bottom surface 164 of the BOP 40. In some embodiments, the seconddistance 168 is slightly larger than the first distance 162 such that agap 170 is formed between the surface 166 of the second shearing portion68 and the ledge 160 of the first shearing portion 66. Accordingly, thefirst ram 50 and the second ram 52 may each extend through the tubularstring 24 to completely cut the tubular string 24, and thus seal thebore 25.

Similar to movement of the first ram 50, as the hydraulic fluid 124enters the first hydraulic chamber 128 and directs the second actuator129 in the direction 88, the second hydraulic fluid 130 may flow from asecond hydraulic chamber 142 of the second actuator 129 toward one ormore of the hydraulic accumulators 45. In some embodiments, a pressuremay increase in the second hydraulic chamber 142 as the second actuator129 moves in the direction 88 (e.g., as a result of a reduction involume of the second hydraulic chamber 142 caused by the piston 62).Accordingly, the pressure within the second hydraulic chamber 142 mayurge the second hydraulic fluid 130 through an outlet 144 of the secondhydraulic chamber 142 and toward one or more of the hydraulicaccumulators 45.

In some embodiments, the hydraulic fluid 124 flows toward the firsthydraulic chamber 128 of the second actuator 129 through a piloted checkvalve 172. The piloted check valve 172 may include a default position174 configured to enable the hydraulic fluid 124 to flow in a firstdirection 176 toward the second actuator 129. The piloted check valve172 may additionally block flow of the hydraulic fluid 124 in a seconddirection 178 (e.g., from the second actuator 129 toward the pilotedcheck valve 172 and/or the sequencing valve 120). As shown in theillustrated embodiment of FIG. 7, the piloted check valve 172 may befluidly coupled to the second hydraulic chamber 142 of the secondactuator 129. When the pressure within the second hydraulic chamber 142of the second actuator 129 increases to a value that meets or exceeds athreshold pressure (e.g., as a result of a reduction in volume of thesecond hydraulic chamber 142 as the second actuator 129 moves in thedirection 88), the piloted check valve 172 may be configured to trigger,thereby enabling flow of the hydraulic fluid 124 in the second direction178 and blocking flow of the hydraulic fluid in the first direction 176.In some embodiments, when the hydraulic fluid 124 flows in the seconddirection 178, the second ram 52 may be driven toward the open position54 by the second actuator 129 (e.g., via the second hydraulic fluid 130being pumped into the second hydraulic chamber 142 via a second pump180).

When blowout conditions subside (e.g., the pressure of fluid in the welldecreases below a threshold pressure), the rams 50, 52 may both bedriven to the open position 54 to unseal the bore 25. For example, itmay be desirable to open the bore 25 and enable fluid to flow toward theplatform 12 when blowout conditions no longer exist. FIG. 8 is aschematic of a portion of the BOP 40, illustrating the hydraulic circuit122 directing the hydraulic fluid 124 such that the rams 50, 52 aredriven to the open position 54. As shown in the illustrated embodiment,the piloted check valve 172 is triggered, thereby enabling flow of thehydraulic fluid 124 in the second direction 178 (e.g., from the secondactuator 129 toward the sequencing valve 120). Accordingly, thehydraulic fluid 124 may drain from both the first hydraulic chamber 126of the first actuator 127 and the first hydraulic chamber 128 of thesecond actuator 129 toward a hydraulic fluid reservoir (e.g., one ormore of the hydraulic accumulators 45).

For example, the second pump 180 may direct the second hydraulic fluid130 from one or more of the hydraulic accumulators 45 toward the secondhydraulic chamber 131 of the first actuator 127 and toward the secondhydraulic chamber 142 of the second actuator 129. Therefore, pressureswithin the second hydraulic chambers 131, 142 may increase, therebydriving the first and second actuators 127, 129 toward the open position54 (e.g., the first actuator 127 is driven in the direction 88 and thesecond actuator is driven in the direction 86).

In some embodiments, the first pump 125 and/or the second pump 180 maybe coupled to the controller 46, which may be configured to adjust aspeed of the first and second pumps 125, 180 to control movement of theactuators 127, 129. For example, the controller 46 may becommunicatively coupled to motors of the first and second pumps 125, 180such that the controller 46 may adjust the speed of the motors, andthus, the amount of the hydraulic fluid 124, 139 directed toward theactuators 127, 129.

Moving the rams 50, 52 to the second positions 100, 140, respectively,may be performed in the sequence described above (e.g., driving thefirst ram 50 to the second position 100 before driving the second ram 52into the second position 140). However, directing the rams 50, 52 to theopen position 54 (e.g., from the second positions 100, 140) may occursimultaneously or sequentially. Therefore, the bore 25 may be opened ina single step, whereas sealing the bore 25 may occur utilizing themulti-step, enhanced shearing sequence.

It should be noted that, in other embodiments, other components (e.g.,instead of the sequencing valve 120 and the piloted check valve 172) maybe utilized to perform the enhanced shearing sequence. For example, anysuitable combination of valves and conduits may be utilized to directthe first ram 50 to the second position 100, while leaving the secondram 52 substantially stationary as a first step, and then directing thesecond ram 52 to the second position 140 after the first ram 50 reachesthe second position 100 as a second step.

FIG. 9 is a block diagram 200 of a process for performing the enhancedshearing sequence to enhance a seal of the bore 25 when blowoutconditions exist. At block 202, the controller 46 may be configured toactuate the first ram 50 toward the tubular string 24 disposed in thebore 25 of the riser 22. As discussed above, the first ram 50 may bepositioned adjacent to the first end 64 of the body 56 of the BOP 40(e.g., on a first side of the bore 25). In some embodiments, the firstram may be actuated toward the tubular string 24 by directing thehydraulic fluid 124 through the sequencing valve 120 toward the firsthydraulic chamber 126 of the first actuator 127. Additionally, thehydraulic fluid 124 may be blocked from flowing toward the secondactuator 129 by the sequencing valve 120 when the pressure of thehydraulic fluid 120 is below the threshold pressure, thereby maintainingthe second ram 52 in the open position 54.

At block 204, the first ram 50 may guide the tubular string 24 along theinner diameter 102 of the bore 25 such that the tubular string 24 isgenerally aligned with the first shearing portion 66 and the secondshearing portion 68 of the first and second rams 50, 52 along the axis101. As discussed above, the second ram 50 may be positioned adjacent tothe second end 65 of the body 56 of the BOP 40 (e.g., on a second sideof the bore 25 opposite the first side).

At block 206, the controller 46 may be configured to actuate the secondram 52 toward the tubular string 24 and toward the first ram 52. Asdiscussed above, the sequencing valve 120 may trigger when the pressureof the hydraulic fluid 124 meets or exceeds the threshold pressure,thereby opening the outlet 134 coupled to the second actuator 129.Therefore, the second ram 52 may be directed toward the tubular string24 and the first ram 50 as the hydraulic fluid 124 flows toward thefirst hydraulic chamber 128 of the second actuator 129. Additionally,the first ram 52 may remain substantially stationary such that opposingforces are applied to the tubular string 24 by the first ram 50 and thesecond ram 52. Accordingly, the first ram 50 and the second ram 52 maycut through the entire tubular string 24 such that the bore 25 may besealed when blowout conditions are experienced at the wellhead.

While the present disclosure may be susceptible to various modificationsand alternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the present disclosure is notintended to be limited to the particular forms disclosed. Rather, thepresent disclosure is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the presentdisclosure as defined by the following appended claims.

1. A blowout preventer system, comprising: a body surrounding a boreconfigured to enable fluid flow between a wellhead and a drilling riser;a first ram disposed adjacent a first end of the body, wherein the firstram is coupled to a first actuator; a second ram disposed adjacent to asecond end opposite the first end of the body, wherein the second ram iscoupled to a second actuator; and a controller communicatively coupledto the first actuator and the second actuator, wherein the controller isconfigured to actuate the first actuator to direct the first ram towarda tubular string disposed in the bore, such that the first ram alignsthe tubular string with a first shearing portion of the second ram whenthe first ram is in an actuated position, and wherein the controller isconfigured to actuate the second actuator, after actuating the firstactuator, to direct the second ram toward the tubular string such thatthe first ram and the second ram completely cut the tubular string toseal the bore.
 2. The blowout prevention system of claim 1, comprising asequencing valve configured to direct hydraulic fluid toward the firstactuator and configured to block a flow of hydraulic fluid toward thesecond actuator when a first pressure of the hydraulic fluid in thefirst actuator is below a first threshold pressure.
 3. The blowoutprevention system of claim 2, wherein the first threshold pressurecorresponds to a second pressure of the hydraulic fluid in the firstactuator when the first actuator is in the actuated position.
 4. Theblowout prevention system of claim 2, comprising a piloted check valveconfigured to direct the hydraulic fluid from the sequencing valvetoward the second actuator and configured to block the hydraulic fluidfrom flowing toward the sequencing valve from the second actuator when athird pressure of the hydraulic fluid in the first actuator meets orexceeds the first threshold pressure.
 5. The blowout prevention systemof claim 4, wherein the piloted check valve is configured to direct thehydraulic fluid from the second actuator toward the sequencing valvewhen a fourth pressure of the hydraulic fluid in the second actuatorreaches a second threshold pressure.
 6. The blowout prevention system ofclaim 2, comprising a pump configured to drive the hydraulic fluidthrough the sequencing valve.
 7. The blowout prevention system of claim1, comprising a sensor configured to send feedback to the controllerpertaining to a pressure of a fluid at the wellhead, wherein thecontroller is configured to compare the feedback to a threshold value.8. The blowout prevention system of claim 7, wherein the controller isconfigured to actuate one or both of the first and second actuators onlywhen the feedback meets or exceeds the threshold value.
 9. The blowoutprevention system of claim 1, wherein the first ram comprises a secondshearing portion comprising a linear geometry and the first shearingportion of the second ram comprises an indented geometry.
 10. A system,comprising: a bore extending between a wellhead and a drilling riser; atubular string disposed in the bore and configured to direct a fluidbetween the wellhead and the drilling riser; a blowout preventer coupledto the wellhead, wherein the blowout preventer comprises a bodysurrounding the bore and the tubular string; a first ram of the blowoutpreventer positioned on a first side of the bore, wherein the first ramcomprises a first shearing portion and is coupled to a first actuator; asecond ram of the blowout preventer positioned on a second side of thebore opposite the first side, wherein the second ram comprises a secondshearing portion and is coupled to a second actuator; and a controllercoupled to the first actuator and the second actuator, wherein thecontroller is configured to actuate the first actuator to direct thefirst ram toward the tubular string and configured to actuate the secondactuator to direct the second ram toward the tubular string afteractuating the first actuator.
 11. The system of claim 10, comprising ahydraulic circuit configured to flow a hydraulic fluid to and from ahydraulic accumulator, the first actuator, and the second actuator. 12.The system of claim 11, wherein the hydraulic circuit comprises asequencing valve configured to direct hydraulic fluid toward the firstactuator and to block a flow of the hydraulic fluid toward the secondactuator when a first pressure of the hydraulic fluid in the firstactuator is below a first threshold pressure.
 13. The system of claim12, comprising a piloted check valve configured to direct the hydraulicfluid from the sequencing valve toward the second actuator and block thehydraulic fluid from flowing toward the sequencing valve from the secondactuator when a second pressure of the hydraulic fluid in the firstactuator meets or exceeds the first threshold pressure.
 14. The systemof claim 13, wherein the piloted check valve is configured to direct thehydraulic fluid from the second actuator toward the sequencing valvewhen a third pressure of the hydraulic fluid in the second actuatorreaches a second threshold pressure.
 15. The system of claim 10, whereinthe first shearing portion of the first ram comprises a linear geometryand the second shearing portion of the second ram comprises an indentedgeometry.
 16. A method, comprising: actuating a first ram of a blowoutpreventer toward a tubular string disposed in a bore of the blowoutpreventer, wherein the first ram is disposed on a first side of thebore; aligning the tubular string with a first shearing portion of asecond ram disposed on a second side of the bore opposite the firstside; and actuating the second ram toward the tubular string and thefirst ram, such that the first ram and the second ram cut the tubularstring to seal the bore.
 17. The method of claim 16, wherein actuatingthe first ram of the blowout preventer toward a tubular string disposedin the bore of the drilling riser comprises directing hydraulic fluidthrough a sequencing valve and toward a first actuator coupled to thefirst ram.
 18. The method of claim 17, wherein directing the hydraulicfluid through the first sequencing valve and toward the first actuatorcoupled to the first ram comprises blocking the hydraulic fluid fromflowing toward a second actuator coupled to the second ram when apressure of the hydraulic fluid in the first actuator is below athreshold pressure.
 19. The method of claim 18, wherein actuating thesecond ram toward the tubular string and the first ram such that thefirst ram and the second ram completely cut the tubular string to sealthe bore comprises directing the hydraulic fluid through the sequencingvalve toward the second actuator coupled to the second ram when thepressure of the hydraulic fluid in the first actuator meets or exceedsthe threshold pressure.
 20. The method of claim 16, wherein aligning thetubular string with the first shearing portion of the second ramdisposed on the second side of the bore opposite the first sidecomprises guiding the tubular string along an inner diameter of thebore, such that the tubular string is aligned with the first shearingportion and a second shearing portion of the first ram with respect to alongitudinal axis.